🌱 initial: First draft.

Author: make-github-pseudonymous-again

README.md

@@ -4,12 +4,10 @@
 Test whether an array-like is a palindrome for JavaScript.
 See [docs](https://array-like.github.io/is-palindrome/index.html).
 
-> :building_construction: Caveat emptor! This is work in progress. Code may be
-> working. Documentation may be present. Coherence may be. Maybe.
-
-> :warning: Depending on your environment, the code may require
-> `regeneratorRuntime` to be defined, for instance by importing
-> [regenerator-runtime/runtime](https://www.npmjs.com/package/regenerator-runtime).
+```js
+import {isPalindrome} from '@array-like/is-palindrome';
+isPalindrome('ΝΙΨΟΝΑΝΟΜΗΜΑΤΑΜΗΜΟΝΑΝΟΨΙΝ'); // true
+```
 
 [![License](https://img.shields.io/github/license/array-like/is-palindrome.svg)](https://raw.githubusercontent.com/array-like/is-palindrome/main/LICENSE)
 [![Version](https://img.shields.io/npm/v/@array-like/is-palindrome.svg)](https://www.npmjs.org/package/@array-like/is-palindrome)

doc/manual/usage.md

@@ -1,19 +1,8 @@
 # Usage
 
-> :warning: Depending on your environment, the code may require
-> `regeneratorRuntime` to be defined, for instance by importing
-> [regenerator-runtime/runtime](https://www.npmjs.com/package/regenerator-runtime).
-
-First, require the polyfill at the entry point of your application
-```js
-await import('regenerator-runtime/runtime.js');
-// or
-import 'regenerator-runtime/runtime.js';
-```
-
-Then, import the library where needed
+Import the library where needed
 ```js
-const isPalindrome = await import('@array-like/is-palindrome');
+const {isPalindrome} = await import('@array-like/is-palindrome');
 // or
-import * as isPalindrome from '@array-like/is-palindrome';
+import {isPalindrome} from '@array-like/is-palindrome';
 ```

src/_isPalindrome.js

@@ -0,0 +1,17 @@
+/**
+ * Tests whether a slice of an array-like is a palindrome.
+ *
+ * @param {ArrayLike} a Array-like input
+ * @param {number} i Inclusive left bound
+ * @param {number} j Non-inclusive right bound
+ * @return boolean True if the input slice is a palindrome.
+ */
+export default function _isPalindrome(a, i, j) {
+	while (i < j) {
+		if (a[i++] !== a[--j]) {
+			return false;
+		}
+	}
+
+	return true;
+}

src/index.js

@@ -1,2 +1,2 @@
-const answer = 42;
-export default answer;
+export {default as _isPalindrome} from './_isPalindrome.js';
+export {default as isPalindrome} from './isPalindrome.js';

src/isPalindrome.js

@@ -0,0 +1,11 @@
+import _isPalindrome from './_isPalindrome.js';
+
+/**
+ * Tests whether an array-like is a palindrome.
+ *
+ * @param {ArrayLike} a Array-like input
+ * @return boolean True if the input is a palindrome.
+ */
+export default function isPalindrome(a) {
+	return _isPalindrome(a, 0, a.length);
+}

test/src/api.js

@@ -1,5 +1,25 @@
 import test from 'ava';
 
-test('API', (t) => {
-	t.fail();
-});
+import {isPalindrome} from '../../src/index.js';
+
+const macro = (t, s, expected) => {
+	t.is(expected, isPalindrome(s));
+};
+
+macro.title = (title, s, expected) =>
+	title ?? expected ? `'${s}' is a palindrome` : `'${s}' is not a palindrome`;
+
+test(macro, '', true);
+test(macro, 'Ö', true);
+test(macro, 'x', true);
+test(macro, 'xx', true);
+test(macro, 'xyx', true);
+test(macro, 'sator arepo tenet opera rotas', true);
+test(macro, 'ΝΙΨΟΝΑΝΟΜΗΜΑΤΑΜΗΜΟΝΑΝΟΨΙΝ', true);
+
+test(macro, 'ab', false);
+test(macro, 'abc', false);
+test(macro, 'abca', false);
+test(macro, 'sator arepo tenët opera rotas', false);
+test(macro, 'Sator Arepo Tenet Opera Rotas', false);
+test(macro, 'ΝΙΨΟΝ ΑΝΟΜΗΜΑΤΑ ΜΗ ΜΟΝΑΝ ΟΨΙΝ', false);